Write a program that finds the second largest element in a given list of N numbers.

Data Structure Searching (Article) Searching (Program)

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Program:

/* This program finds the second largest in a given list of numbers */

#include <stdio.h>

int Num, firstLarge, secLarge;

int N, i;

void main()

{

printf ("\n Enter the size of the list");

scanf ("%d", & N);

printf ("\n Enter the list one by one");

scanf ("%d", &Num);

firstLarge = Num;

secLarge = - 9999;

for (i = 2; i <= N; i++)

{

  scanf ("%d", &Num);

  if (firstLarge < Num)

  {secLarge = firstLarge;

  firstLarge = Num;

  }

  else

    if (secLarge < Num)

    secLarge = Num;

}

printf ("\n Second Large = %d", secLarge);

}

Output:

Enter the size of the list: 5                                                                                                     
                                                                                                                                 
 Enter the list one by one
1                                                                                                      
2                                                                                                                                
3                                                                                                                                
4                                                                                                                                
5

Explanation:

The above discussed search through a list, stored in an array, has the following characteristics:

  • The search is linear.
  • The search starts from the first element and continues in a sequential fashion from element to element till the desired entry is found.
  • In the worst case, a total number of N steps need to be taken for a list of size N.

Thus, the linear search is slow and to some extent inefficient. In special circumstances, faster searches can be applied.

For instance, binary search is a faster method as compared to linear search. It mimics the process of searching a name in a directory wherein one opens a page in the middle of the directory and examines the page for the required name. If it is found, the search stops; otherwise, the search is applied either to first half of the directory or to the second half.

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